What was the first Mormon church built?

Exactly what counts as the "first" Church Meetinghouse of the Church of Jesus Christ of Latter-day Saints (commonly called the "Mormon" Church) is actually somewhat debated by scholars. Church Meetinghouses were extremely rare in the Church until well after the headquarters and members moved to Salt Lake City, about 20 years after the first Church meetings were held. Most Church meetings were held outdoors, in private homes, or in barns.

Some consider the Gadfield Elm chapel in Pendock, England to be the first meetinghouse of the Church. This chapel was built in 1836 by a religious society called the "United Bretheren". The majority of the United Bretheren congregation converted to Mormonism and their meetinghouse was deeded over to the Church in 1840. However, just a few years later, the building was sold to fund the immigration of English Church members to the United States. Since it was not originally built by the Church, and since it was not owned by the Church for nearly 100 years (the building was re-purchased by the Church in 1994), it is usually called 'the oldest Mormon church in England', but not the oldest church worldwide.
When Church membership moved to Illinois, a community was set up in Ramus (now called Webster). The Mormon congregation in Ramus built their own Church Meetinghouse in the early 1840's. The Ramus meetinghouse was abandoned when the last Church members left Ramus in the 1850's, and was replaced in 1897 by Webster Community Church. Although this is often considered the first "Mormon-built" meetinghouse, it is only considered so because there is no surviving record of a meetinghouse built earlier.
The Pine Valley Chapel in Pine Valley, Utah is the oldest Mormon Church Meetinghouse in continuous use. It was built in 1868 and continues to hold regular Sunday meetings today. This is more often considered the "oldest" meetinghouse rather than the "first", but it is much better known because unlike the meetinghouse in Ramus, this one still stands and is still used. Of course, there were Church Meetinghouses in Utah built prior to the Pine Valley Chapel, but none of them are still in existence today.
The Church built buildings for other purposes which were sometimes used to hold Sunday services. For example, the Kirtland Temple in Kirtland, Ohio is usually considered the oldest Mormon building, but it is not considered a meetinghouse. It was completed in 1836. However, like all Mormon Temples, the Kirtland Temple was not used for regular Sunday services. It was most often used as a seminary, school, and administrative offices. Special worship services were held there on occasion, as well as community events. The Kirtland Temple was abandoned by 1840, and is now owned by the Community of Christ. In other places, Tabernacles and Boweries were built. These were not considered meetinghouses, but were used mostly for large Church conferences, for community events, or only temporarily. The vast majority of these buildings no longer stand. Examples of these buildings, along with information about the other buildings mentioned, can be found below under "Related Links".
Exactly what counts as the "first" Church Meetinghouse of the Church of Jesus Christ of Latter-day Saints (commonly called the "Mormon" Church) is actually somewhat debated by scholars. Church Meetinghouses were extremely rare in the Church until well after the headquarters and members moved to Salt Lake City, about 20 years after the first Church meetings were held. Most Church meetings were held outdoors, in private homes, or in barns.

Some consider the Gadfield Elm chapel in Pendock, England to be the first meetinghouse of the Church. This chapel was built in 1836 by a religious society called the "United Bretheren". The majority of the United Bretheren congregation converted to Mormonism and their meetinghouse was deeded over to the Church in 1840. However, just a few years later, the building was sold to fund the immigration of English Church members to the United States. Since it was not originally built by the Church, and since it was not owned by the Church for nearly 100 years (the building was re-purchased by the Church in 1994), it is usually called 'the oldest Mormon church in England', but not the oldest church worldwide.
When Church membership moved to Illinois, a community was set up in Ramus (now called Webster). The Mormon congregation in Ramus built their own Church Meetinghouse in the early 1840's. The Ramus meetinghouse was abandoned when the last Church members left Ramus in the 1850's, and was replaced in 1897 by Webster Community Church. Although this is often considered the first "Mormon-built" meetinghouse, it is only considered so because there is no surviving record of a meetinghouse built earlier.
The Pine Valley Chapel in Pine Valley, Utah is the oldest Mormon Church Meetinghouse in continuous use. It was built in 1868 and continues to hold regular Sunday meetings today. This is more often considered the "oldest" meetinghouse rather than the "first", but it is much better known because unlike the meetinghouse in Ramus, this one still stands and is still used. Of course, there were Church Meetinghouses in Utah built prior to the Pine Valley Chapel, but none of them are still in existence today.
The Church built buildings for other purposes which were sometimes used to hold Sunday services. For example, the Kirtland Temple in Kirtland, Ohio is usually considered the oldest Mormon building, but it is not considered a meetinghouse. It was completed in 1836. However, like all Mormon Temples, the Kirtland Temple was not used for regular Sunday services. It was most often used as a seminary, school, and administrative offices. Special worship services were held there on occasion, as well as community events. The Kirtland Temple was abandoned by 1840, and is now owned by the Community of Christ. In other places, Tabernacles and Boweries were built. These were not considered meetinghouses, but were used mostly for large Church conferences, for community events, or only temporarily. The vast majority of these buildings no longer stand. Examples of these buildings, along with information about the other buildings mentioned, can be found below under "Related Links".